Türker Yıldırım

caching

  • Redis 8 under AGPL, and unpinning a version

    Note2 min read

    The first of May, an open source release again, and a pin from April 2024 that could finally be removed. A decision record that enumerates triggers cannot anticipate…

  • Two years of query logs, read once

    Deep dive10 min read

    A slow query log rotating for two years and never aggregated, and performance work driven by whoever complained loudest.

  • The endpoint that was slow for one customer

    Deep dive9 min read

    A healthy p95 and one customer for whom the endpoint takes four seconds. An aggregate metric that averages away the only case that matters.

  • A licence that came back, and the migration we had prepared

    Deep dive9 min read

    The first of May, an AGPL release, and a decision from April 2024 that can finally be closed — in the direction nobody planned for.

  • A flush-the-cache test that found data with no home

    Note2 min read

    An integration test that clears the cache mid-scenario and asserts the application still behaves. The failure is the point: a preference written to the cache and nowhere else…

  • A cache that was a second database

    Deep dive10 min read

    A cache holding data that existed nowhere else, discovered during a restart. A flush that lost four hours of user preferences.

  • A licence change, and the fork we did not take

    Deep dive10 min read

    20 March, a licence change, and a fork announced within a week. A dependency that is no longer open source, in production, everywhere.

  • A cache with persistence turned on to hide a design problem

    Note2 min read

    Turning on persistence so a restart would stop losing data, which is treating the symptom of data that should not have been there. Persistence on a cache is…

  • Two caches with the same key and different meanings

    Note2 min read

    Two services writing settings:41, one meaning customer 41 and one meaning tenant 41, against the same instance. Separate logical databases on one instance are the other answer and…

  • Cache keys audited for what writes them

    Note2 min read

    An audit of every cache key, asking one question each: if this disappeared, could it be regenerated? A cache that holds the only copy of something is a…